Gear lapping



W. S. PRAEG GEAR LAPPING Feb. 13, 1951 2,541,283

Filed July 6, 1948 3 Sheets-Sheet 1 INVENTOR.

WALTER S. PRAEG yjimw,w y/g/w ATTORNEYS Feb. 13, 1951 W. S. PRAEG GEARLAPPING Filed July 6, 1948 3 Sheets-Sheet 3 WvA M WALTER S. PRA EG ATTORN EYS Patented Feb. 13, 1951 2,541,283 GEAR LAPPING Walter S. Pracg,Detroit, Mich., assignor to National Broach & Machine Company, Detroit,Mich., a corporation of Michigan Application July s, 1948, Serial No.31,132

7 Claims.

The present invention relates to apparatus for lapping gears and moreparticularly to a machine including mechanism for feeding lappingcompound into the meshing zone.

It is an object of the present invention to provide in a gear lappingmachine mechanism for feeding lapping compound into the zone of meshbetween a gear-like lap and a gear in predetermined amounts and atpredetermined intervals.

More specifically, it is an object of the present invention to providemeans for feeding a semisolid lapping compound between a gear andgearlike lap, including a flattened nozzle to supply the semifiuidlapping compound in ribbon form.

It is a further object of the present invention to provide a gearlapping machine comprising means for rolling a gear and gear-like lap inmesh, means for relatively reciprocating a gear and gear-like lap in adirection which occupies a plane parallel to the axes of both the gearand lap, means for reversing the rotation of the gear and lap at the endof a stroke. of reciprocation, and automatic means for feeding apredetermined amount of semisolid lapping compound into the zone of meshbetween the gear and lap at the approach side of the teeth thereof.

Other objects and features of the invention will become apparent as thedescription proceeds, especially when taken in conjunction with theaccompanying drawings, wherein:

Figure 1 is a front elevation of a gear lapping machine embodying thepresent invention;

Figure 2 is a top plan view of a portion of the means for feedinglapping compound;

Figure 3 is a section taken on the line 3-3 of Figure 2; and

Figure 4 is a partly schematic wiring diagram of the gear lappingmachine.

Referring now to Figure 1 the gear lapping machine comprises a base lhaving an upwardly extending pedestal l l terminating in a forwardlyprojecting overhanging portion 12. Angularly adjustable about a verticalaxis beneath the overhanging portion I2 is a rotary support l3 includingmeans for mounting a gear-like member ll thereon. Drive means includingthe motor (not shown) are mounted in the portion l2 and are connected tothe gear-like member I4 through suitable driving mechanism.

On the forward portion of the column II is a vertically adjustable kneel5 upon which is mounted a carriage l6. Intermediate the carriage l6 andthe knee l5 are horizontally extending ways by virtue of which the tableIt may be reciprocated back and forth, that is from disclosed inDrummond Patent 2,157,981.

right to left as seen in Figure 1. Details of this mechanism form nopart of the present invention and are fully disclosed in Drummond Patent2,270,421.

Located on the carriage i6 is a rocking table 20 which is pivoted to thetable for rocking motion about a horizontal axis as by a trunnionindicated at 2 i. Suitable cam means indicated genorally at 22 areprovided and are rigidly mounted on the column l5. The cam followercarried by the rocking table 20 engages the cam and may be employed toeffect a predetermined rocking movement of the table 20 in timedrelation and in response to back and forth reciprocation of the carriagel6. Details of this construction form no part of the present inventionand are fully The rocking table 20 carries at its top a support member25 which is mounted for angular adjustment with respect to the table 20about a vertical axis and which is adapted to be clamped in adjustedposition by suitable means (not shown). Adjustable stocks 28, 29 areprovided on the support member 25 for supporting therebetween a secondgear-like member 30.

The gear-like members It and 30 may be brought into engagement byvertical adjustment of the knee IS on the column III. In this type ofgear finishing it is desired to have the axes of the gear-like partscrossed at an angle between 3 and 30 degreesand this condition may bebrought about by angular adjustment of the adjustable support l3 or thesupporting member 25 or both. As previously stated, means are providedfor efiecting back and forth reciprocation of the carriage I6. It willbe readily apparent that by appropriate adjustment of the angularadjustment of the support 13 and the supporting member 25, the desiredangularity between the direction of reciprocation and the axes of thegear-like parts may be achieved.

Suitable driving means are provided for effecting back and forthreciprocation of the carriage l6 and for effecting rotation of thepositively driven gear-like member l4. Suitable controls are alsoprovided and these may take the form of switch actuating dogs 35 and 36adapted to be engaged upon reciprocation of the carriage l8- byadjustable bolts 31 and 38. By this means reciprocation of the carriageI6 is limited by engagement between a bolt 31 and a dog 35 on the onehand and bolt 38 and dog 36 on the other hand. Furthermore, thedirection of rotation of the members [4 and 30 is preferably reversed atthe end of each stroke of reciprocation and the switches controlled bythe dogs 35 and 38 may effect this reversal of rotation.

The lapping operation is normally carried out with a cast iron lap andin order to remove metal from the part being lapped, a suitable abrasivelapping compougi is introduced onto the teeth of the lap. In the pastthis has been accomplished in a crude manner by dipping a brush inlapping compound and brushing the teeth of the lap. This results in verypoor control of the amount of lapping compound applied and further agood part of the lapping compound may bethrown off by centrifugal actionand waste.

In accordance with the present invention a relatively viscous orsemisolid lapping compound is employed and it is applied inpredetermined equal amounts at definite intervals during the lappingoperation. Furthermore, it is applied in the form of a thin ribbon sothat it will appear uniformly from end to end of the teeth of the lap.

The means for feeding lapping compound includes a reservoir 39, and aflexible conduit 40 terminating in a flattened nozzle 4| which is.

located adjacent the zone of mesh between the gear-like members l4 and-30. It may be mentioned at this time that either the member l4 or themember 30 may be the lap, the other of these two members of course beingthe gear to be lapped.

In order to apply the lapping compound for maximum emciency and with a,minimum of waste it isdesirable to apply the lapping compound in theform of a thin ribbon directly into the bight at the zone of meshbetween the gear and the lap, and furthermore, to so time the compoundfeeding operation that the lapping compound is introduced onto the teethof the gear and lap at the approach side of mesh. It is furtherdesirable for the feeding operation to take place in such a. manner thatlapping compound is spread more or less uniformly around the peripheryof the lap and/or gear. However, since the teeth of the lap and gearwill in all cases be of different number, and since the rate of rotationof these parts is relatively high, lapping compound will be spread moreor less uniformly due to the meshing engagement of the teeth of the gearand lap.

Referring now specifically to Figures 2 and- 3 the compound feedingstructure comprises the reservoir or container 39 which as best seen inFigure 2 is of generally U-shaped cross section having a recess 42provided therein for the reception of the feeding mechanism indicatedgenerally at 43. The reservoir 39 has a hinged cover 44 which may beraised to supply the semisolid or viscous lapping compound to thereservoir. At the bottom of the recess 42 is a ledge 45 having anopening therein in which is provided a flexible diaphragm 46 which maybe formed of neoprene or other suitable material. Connected centrally tothe diaphragm 46 is a plunger 41, the lower end of which extends into ashort tubular bushing. or sleeve 48 provided in the bottom wall 49 ofthe reservoir 39. Secured to theupper end of the plunger 41 is a rod 50which is connected at its upper end as indicated at to the core 52 of asolenoid 53 having windings indicated at 54. A compression spring 55 isprovided between a disc 56 connected to the upper end of the plunger 41and a head 51 formed on a tubular guide 58 in which the rod 56reciprocates.

At the lower end of the sleeve 48 is the flexible tube 43 terminating inthe flattened nozzle 41 previously referred to. The conduit 46 may be infact particular means have been designed to permit pressure feeding ofthis fiuid by a mechanism which will not be subjected to excessive wearby the abrasive. For this purpose the sleeve 48 has an internal diametersufliciently larger prevent wear taking place between these surfaces.

l On the other hand the amount of clearance is sufliciently small sothat these two elements operate efliciently as a force feeding devicefor a semisolid material.

It is. desirable in feeding this abrasive compound to provide arelatively slow feed and accordingly, the plunger 41 is connected to thesolenoid 53 in such a manner that upon energization of the solenoid theplunger 41 is withdrawn from the sleeve 48 by an amount sufficient topermit now of compound into the sleeve. The operation of the solenoid isof course extremely rapid but the withdrawing stroke of the plunger 41is not a pumping stroke. When the solenoid 53 is de-energized theplunger 41 is urged toward and into the sleeve 48 by the compressionspring 55. The strength of the compression spring 55 is selected suchthat a relatively slow control movement of the plunger 41 results.Accordingly, lapping compound is expelled from the flattened nozzle 42at a controlled rate. Due to the flattened shape of the nozzle 41 theabrasive compound is formed into aribbon which is thus spread upon theteeth of the gear or lap.

The'circuit in which the windings 54 of the solenoid are included isconnected to the switches actuated by the dogs 35 and/or 36 so that thefeeding of the lapping compound takes place at the end of a stroke andfurther at a time when the rotation of the parts [4 and 34 is away fromthe nozzle 4|. Accordingly, lapping compound is immediately rolledbetween the teeth of the parts before any of the material can be thrownoff by centrifugal action.

Referring now to Figure 4 the control mechanism is illustrated. Thereciprocable carriage I6 is designated to be reciprocated back and forthby a conventional feed screw mechanism comprising a feed nut 60 and feedscrew 62, the latter being driven'through a gear box 63 from a motor 64.The switch actuating dogs 35 and 38 previously referred to are connectedto normally open switches 65 and 66 respectively, which are adapted tobe closed by engagement with the adjustable bolts 31 and 38 respectivelyas the table reaches either limit of its stroke. The motor 64 isconnected to a three phase circuit 68 through a reversing contactor 69.

Reversing the motor 64 by switches 65 or 66 is accomplished bycompleting a circuit from line 10, line 12, switch 66, line 13, to thereversing contactor, the circuit being completed through operate asolenoid therein to eil'ect reversing of the lines 18 and 11 to themotor. At the same time as a circuit is completed through the switch 08,a circuit is completed through the solenoid winding 54 through a line18, switch 19, line 80, td'the solenoid windings and thence through theline 8! to the power supply. The switch ll is a double-throw switchwhich may cause the solenoid winding 54 to beenergized when either theswitch 88 or'the switch 65 is closed, but not both.

Reversal of the reversing contactors by closing the circuit through thelines 13 and I4 reverses the motor 6.4 and causes initiation of reversetraverse of the table I 8. Eventually the dog 65 engages the bolt 31 andcloses switch 65. At this time a circuit is completed through line 82,switch 65, and line 83 to the reversing contactor from whence thecircuit is completed by a line 84 to the power supply. Completion ofthis circuit energizes an additional solenoid in the reversing contactorin the usual way and reverses the connections to the motor 64. At thesame time, a circuit is set up through line 8!, switch 19, line 80, tothe solenoid winding 54, and thence through the line 8| to the powersupply.

Thus, by a proper selection of the switch 19 the solenoid 54 may beenergized upon completion of a stroke oftraverse in either directiomandas previously indicated, this direction of traverse is selected suchthat as the abrasive compound is fed into the gear and lap, it is fed ata time when the adjacent portions of the gear teeth and lap teeth aremoving away from the nozzle 4| so that the compound is introducedimmediately into the point of meshing engagement between the teeth.

The drawings and the foregoing specification constitute a description ofthe improved gear lapping in such full, clear, concise and exact termsas tov enable any person skilled in the art to practice the invention,the scope of which is indicated by the appended claims.

What I claim as my invention is: I

1. In a gear lapping machine, pressure feeding means for lappingcompound comprising a container having a recessed side wall spaced abovethe bottom wall of said container, a sleeve in the bottom wall of saidcontainer, the said recessed side wall providing a ledge spaced above Isaid sleeve, said ledge having an opening therein, 7

a flexible diaphragm closing said opening, a plunger connected to saiddiaphragm having a portion movable into and out of the upper end of saidsleeve to expel lapping compound from said container, a solenoid forraising said plunger, and spring means for moving said plungerdownwardly into said sleeve.

2. In a gear lapping machine, pressurefeeding means for lapping compoundcomprising a con tainer having a recessed side wall spaced above thebottom wall of said container, a sleeve in the bottom wall of saidcontainer, the said recessed side wall providing a ledge spaced abovesaid of said reservoir beneath the level of lapping compound therein, aplunger in said reservoir having a loose lit in said sleeve and movablebetween a charging position in which the end of said plunger iswithdrawn from an end of said sleeve and a feeding position in whichsaid plunger enters said sleeve to expel compound from the other endthereof and means for actuating said plunger.

4. In a gear lapping machine, pressure feeding means for lappingcompound comprising a reservoir, a tubular sleeve extending through awall of said reservoir beneath the level of lapping compound therein, aplunger in said reservoir having a loose fit in said sleeve and movablebetween a charging position in which the end of said plunger iswithdrawn from an end of said sleeve and a feeding position in whichsaid plunger enters said sleeve to expel compound from the other endthereof, a solenoid connected to said plunger for efiecting withdrawalof said plunger from said sleeve, and resilient means for advancing saidplunger on its feeding stroke.

5. In a gear lapping machine, pressure feeding means for lappingcompound comprising a reservoir, a tubular sleeve extending through awall of said reservoir beneath the level of lapping compound therein, aplunger in said reservoir having a loose fit in said sleeve and movablebetween a charging position in which the end of said plunger iswithdrawn from an end of said sleeve and a feeding position in whichsaid plunger enters said sleeve to expel compound from the other endthereof, a solenoid connected to said plunger for effecting withdrawalof said plunger from said sleeve, resilient means for advancing saidplunger on its feeding stroke, and a flexible diaphragm secured to saidplunger and sealing the solenoid mechanism from said sleeve.

6. In a gear lapping machine, a reservoir for semi-solid abrasivelapping compound, a tubular sleeve adjacent the bottom of the reservoiradapted to receive compound by gravity flow and the pressure head of thecompound in the reservoir, a plunger located in alignment with saidsleeve and movable between a position in which the end of said plungerenters said sleeve and a position in which said plunger is withdrawnentirely from said sleeve, said plunger having lateral clearance withrespect to said sleeve to prevent wear by the abrasive compound, aspring urging said plunger toward and into said sleeve, and power meansefiective to withdraw said plunger entirely from said sleeve to permitcharging of said sleeve with compound.

'7. In a gear lapping machine, pressure feeding means for lappingcompound comprising a container having a recessed wall providing a ledgespaced from an adjacent wall, said ledge having an opening therethrough,a sleeve in said adjacent wall aligned with the opening in said ledgeand below the level of lapping compound in said container, plunger meanshaving a plunger portion movable into and out of said sleeve to expellapping compound from said container and a portion extending through theopening in said ledge into the recess, a flexible diaphragm closing theopening in said ledge and secured to said plunger means, and poweractu-' ating means in the recess connected to said plunger means.

WALTER s. PRAEG.

(References on following P le) REFERENCES CITED Number I The followingreferences are of record in the file 0! P t nt: I I v UNITED STATESPATENTS 5 2:851:842

Number Name Date 1,562,138, Copeland Nov. 24, 1925 N be 1,682,420 Rolf1928 :39 J59 1,807,421 Mahoney May 26, 1981 Name Date Drummond Jan. 29,1936 Kampmeier JuLv 8, 1941 Davis Oct. 26, 1943 Belhold June 20, 1944FOREIGN PATENTS- Country Date Germany .4. Sept. 29, 1920

